Hollywood D

I know this has been discussed at nauseaum so I apologize but I couldn't find anything definitive after doing a search. When I start the car up after it's been cold and sitting for a few days it idles around 600rpm and it shakes quite a bit. Once I give it some gas it settles out just fine and the shake goes away. It runs fine once I start going, no hesitation issues or anything.

And once the car gets up to temp it idles just fine at stop lights, etc. If I adjust the idle screw to increase the idle to 900 (when it's cold), wil it affect it once the engine is up to temp? Meaning, if I'm at a stop light will it increase the idle too much (up to around 1300)?

The fact that it idles fine once it's warm makes me think it could be a different problem though. I was planning on replacing some electrical parts just for kicks, such as the dme temp sensor, since they're old anyways and I just want to update them.

Thoughts?

pnbell

"dme temp sensor" or "Idle Air Stabilizer" are suspect. The IAS is located under the Intake Manifold -which has to be removed to get to it- these can get dirty and stick causing similar issues.

Hollywood D

Yea, I just tore it all apart (except for taking the manifold off). I noticed the throttle body is pretty dirty. There's oil in it. I pulled the jboot off and saw that on the bottom vacuum line is where the oil is coming in from. I tried to follow that vacuum line and lost it as it went back down behind the intake manifold. I'm pretty sure there shouldn't be oil in there. Throttle body could use a good cleaning. It's not gummed up but it looks like poopoo.

I suppose the oil in there would be causing the IAS to malfunction.

Butters944

Mine idles at 600 as well, but ends up around 650-700 when warm. Not trying to thread jack here... With my situation should I just adjust my idle screw?

Hollywood D

Not a thread hijack at all, pretty much the same question I have.

ernie9468

First clean the poo out of your throttle body with a "fuel injection/air-intake cleaner" then check all your vacum lines for cracks & make sure they are on thigth.Then adjust the idle to 800 RPM (cold) & take it out for a drive.Like mention by __pnbell__ the "DME temp sensor" or "idle air stab" migth be acting up on you but try what I mention first before buying parts you migth not need.Also very important make sure hose # 7 under your J boot is connected.

Butters944

Thanks, great informational post i was looking for. But I didn't know cars poop...

Ernie to the rescue again!

luftpirate

What is the proper idle speed of an early car, cold/warm? Mine idles around 1000-1100 regardless of whether its cold or warm. Seems to be fine however I wonder if it should be idling lower.

Butters944

I've heard from 900-1100 was factory set range.

BUT when I get mine sorted out my plan is to be at more like 800. Since it idles at 600 right now and has no issues other than a little vibration, I'll just bring it up enough to get rid of the vibration

Jrboulder

Damn that's low. Got a screwdriver?

Butters944

Haha yup. But I wanna follow ernie's instructions first and see if that makes a difference.

Ya know, I really don't mind the low idle- the car sounds beefier at lower idle, and I could care less about the vibrations, lol

Jrboulder

Have you done your AOS seals yet?

ernie9468

Between 900/950 RMP should be rigth on for either early or late car with no vacum/electrical issues.Pics 83-944 93-968. At 1100 it's a little higth.

Butters944

That early pic is at like 800

ernie9468

Open your eyes & take a good look idle is approx at 925 RMP temp if I remember well when the pic was taken was between 1/4 & 1/2 mark.Lol those are 28 years old cars so don't expect miracle.I'll say on an early 944 if idle settle at between 850/950 at operating temp don't temper with it leave it be.